WO2010095634A1 - Solar battery module - Google Patents

Abstract

Disclosed is a solar battery module in which there are alternately provided: a first solar battery cell equipped with a first conductive substrate having a photoreceptor face and non-photoreceptor face, and electrodes having mutually different polarity respectively formed on the photoreceptor face and non-photoreceptor face; and a second solar battery cell equipped with a second conductive substrate having a photoreceptor face and non-photoreceptor face, and electrodes having mutually different polarity respectively formed on the photoreceptor face and non-photoreceptor face.

Description

Solar cell module

The present invention relates to a solar cell module using solar cells that are semiconductor devices.

Solar cell modules manufactured using crystalline solar cells are generally manufactured by connecting cells in series for the purpose of increasing voltage using solar cells that use only one type of conductive substrate. Has been. At this time, when a cell having a first polarity electrode on the light receiving surface side and a second polarity electrode different from the first polarity electrode on the non-light receiving surface side is used, in order to connect them in series The first polarity electrode on the light receiving surface side and the second polarity electrode on the non-light receiving surface side must be connected by a conductive wire (referred to as a tab wire) containing a solder component or the like. The portion of the electrode connected by the tab line is a relatively wide electrode (about 1 to 3 mm) and is generally called a bus bar electrode.

In the above general solar cell module, in order to increase the module conversion efficiency, the solar cells are arranged as close as possible to each other. However, since there is a tab line connecting the electrodes on the light receiving surface side and the non-light receiving surface side, if the cell interval is brought close to a distance of 3.0 mm or less, the cell edge is damaged due to the bending stress of the tab line. There is a problem, which is a cause of reducing the filling rate of solar cells with respect to the area of the solar cell module.

On the other hand, if the thickness of the tab wire itself is reduced to simply reduce the bending stress due to the tab wire, there is a problem that the wiring resistance increases. As another method, for example, JP 2008-147260 A (Patent Document 1) prepares a tab line having a bent portion in advance and connects the tab line so that the bent portion comes between adjacent cells. Thus, a solar cell module has been proposed in which the bending stress of the tab wire is reduced so that the edge of the cell is not damaged.

However, in this method, a tab wire having a special bent portion must be prepared, and since there is a bent portion, there is a drawback that the fill factor of the solar cell module deteriorates as the wiring length by the tab wire increases. is there.

JP 2008-147260 A

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a solar cell module with improved module conversion efficiency by improving the filling rate of solar cells with respect to the area of the solar cell module.

As a result of intensive studies to achieve the above object, the present inventors have formed a first conductive type substrate having a light receiving surface and a non-light receiving surface, and formed on the light receiving surface and the non-light receiving surface, respectively. A first solar cell having electrodes having different polarities, a second conductive type substrate different from the first conductive type having a light receiving surface and a non-light receiving surface, and formed on the light receiving surface and the non-light receiving surface, respectively. The second solar cells having electrodes having different polarities from each other are alternately arranged, so that the first solar cells having the first polarity electrodes on the same plane are different from the first solar cells. Second solar cells having electrodes of two polarities are present side by side, and the electrodes of the light receiving surfaces and the non-light receiving surfaces are connected by a tab line so that series connection is possible. It can be placed close to 0mm or less The module conversion efficiency is improved by improving the packing ratio of the solar cells with respect to the area of the solar cell module, and the tab wire is easy to attach and the stress due to the tab wire is not applied. It has been found that the production yield is increased and a highly reliable solar cell module can be produced, and the present invention has been made.
Of the electrodes on the light-receiving surface and the non-light-receiving surface, a fine electrode formed on the surface of the solar cell in order to collect the output intersecting with the bus bar electrode and having a line width of about 50 to 200 μm is defined as a finger electrode. A thick electrode of about 1 to 3 mm for taking out the output collected by the finger electrodes is called a bus bar electrode.

Accordingly, the present invention provides the following solar cell module.
Claim 1:
A first conductive type substrate having a light receiving surface and a non-light receiving surface, a first solar cell formed on each of the light receiving surface and the non-light receiving surface and having electrodes having different polarities, a light receiving surface and a non-light receiving surface A second conductive substrate having a surface and second solar cells formed on the light receiving surface and the non-light receiving surface and having electrodes having different polarities are alternately arranged. Solar cell module.
Claim 2:
The first and second solar cells have a portion connected in series, and in this serial connection portion, the number of used first solar cells is 50% to 70%, and the second solar cell The solar cell module according to claim 1, wherein the number of cells used is 30% to 50%.
Claim 3:
The solar cell module according to claim 1 or 2, wherein the first conductive type substrate is an N type semiconductor substrate, and the second conductive type substrate is a P type semiconductor substrate.
Claim 4:
The solar cell module according to claim 1, wherein an interval between the solar cells is 0.1 mm or more and 3.0 mm or less.
Claim 5:
The solar cell module according to any one of claims 1 to 4, wherein a difference in short-circuit current density between the first and second solar cells is 20% or less.

By using the solar cell arrangement and wiring method according to the present invention, it is possible to improve the packing ratio of the solar cells with respect to the area of the solar cell module, and to improve the module conversion efficiency. Moreover, since the stress of the tab wire applied to the edge of the solar battery cell can be reduced as compared with the conventional method, the production yield is improved and a highly reliable solar battery module can be manufactured.

The example of the serial connection wiring of the photovoltaic cell in the conventional solar cell module is shown. a is a cross-sectional view, and b is a plan view on the light-receiving surface side. An example of the serial connection wiring of the photovoltaic cell in the solar cell module of this invention is shown. a is a cross-sectional view, and b is a plan view on the light-receiving surface side. It is a top view by the side of the light-receiving surface which shows the example of wiring of the conventional solar cell module whole. It is a top view by the side of the light-receiving surface which shows an example of the wiring of the whole solar cell module of this invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings, but the present invention is not limited to the following embodiments. Note that components having the same function are denoted by the same reference symbols throughout the drawings for describing the embodiment, and the repetitive description thereof will be omitted. In order to make it easy to understand, the interval and thickness of the solar cells are emphasized and illustrated. For simplicity, finger electrodes are omitted.

The solar cell module of the present invention includes a first solar substrate having a light-receiving surface and a non-light-receiving surface, and electrodes formed on the light-receiving surface and the non-light-receiving surface and having different polarities. A second solar cell comprising a battery cell, a second conductive type substrate having a light receiving surface and a non-light receiving surface, and electrodes having different polarities formed on the light receiving surface and the non-light receiving surface, respectively. They are arranged alternately. As shown in FIG. 2, this solar cell module includes solar cells 1 having a first conductivity type substrate and solar cells 2 having a second conductivity type substrate, which are alternately arranged to provide a bus bar electrode 3. Are connected by a tab wire 4. In this case, the conductivity type of the substrate of the first solar cell and the conductivity type of the substrate of the second solar cell are different. For example, when the former is N-type, the latter is P-type. The polarity of the electrode on the light receiving surface of the substrate of the first solar cell and the polarity of the electrode on the non-light receiving surface of the substrate of the second solar cell are the same, and the polarity of the non-light receiving surface of the substrate of the first solar cell The electrode and the electrode on the light receiving surface of the second solar cell have the same polarity. In the present invention, for example, as shown in FIG. 2b, when the light receiving surface of the substrate of the first solar cell is disposed on the upper side, the light receiving surface of the substrate of the second solar cell is disposed on the upper side. The electrode on the light receiving surface of the first solar cell and the electrode on the light receiving surface of the second solar cell are connected in a straight line on the same surface without having a bent portion.

In this case, the conductivity type, impurity diffusion layer, antireflection film, etc. of the substrate constituting the solar battery cell used in the present invention can be in a known manner, and a known method described in JP-A-2001-77386, etc. Can be manufactured.

As the semiconductor substrate constituting the solar battery cell of the present invention, for example, a P-type or N-type single crystal silicon substrate, a P-type or N-type polycrystalline silicon substrate, a non-silicon compound semiconductor substrate, or the like can be used. When a single crystal silicon substrate is used, an as-cut single crystal {100} P type silicon substrate or the like having a specific resistance of 0.1 to 5 Ω · cm by doping high purity silicon with a group III element such as boron or gallium is used. Can do. Further, a similar N-type silicon substrate doped with a group V element such as phosphorus, antimony, or arsenic can be used.

In this case, as the purity of the single crystal silicon substrate used in the present invention, a high-efficiency solar cell can be manufactured by using a high lifetime substrate when the concentration of metal impurities such as iron, aluminum, and titanium is lower. To preferred. This single crystal silicon substrate may be produced by any method such as CZ method, FZ method, etc. In this case, a metal grade silicon previously purified by a known method such as Siemens method may be used in the above method. it can.

The thickness of the semiconductor substrate is preferably 100 to 300 μm, more preferably 150 to 250 μm, from the viewpoint of the cost of the substrate, the yield, and the conversion efficiency. In addition, if the specific resistance of the semiconductor substrate is smaller than the above range, the conversion efficiency distribution of the solar battery cell becomes small, but because it is limited in pulling up the ingot, the crystal cost may increase. Although the distribution of conversion efficiency increases, the crystal cost may decrease.

In the present invention, the first conductivity type may be N-type or P-type. The second conductivity type may be selected by selecting the P-type when the N-type is selected as the first conductivity type, and selecting the N-type when the P-type is selected as the first conductivity type.

The substrate surface is preferably formed with minute irregularities called textures. Texture is an effective way to reduce the surface reflectance of solar cells. This texture is easily produced by dipping in an aqueous alkali solution such as heated sodium hydroxide.

In the impurity diffusion layer, Group V elements such as phosphorus, arsenic, and antimony, and Group III elements such as boron, aluminum, and gallium can be used as an impurity source. Specifically, for example, an impurity diffusion layer can be formed by a vapor phase diffusion method using phosphorus oxychloride or the like for phosphorus diffusion. In this case, heat treatment is preferably performed at 850 to 900 ° C. for 20 to 40 minutes in an atmosphere such as phosphorus oxychloride. The thickness of the impurity diffusion layer is preferably 0.1 to 3.0 μm, more preferably 0.5 to 2.0 μm. If the thickness is too thick, the number of sites where electrons and holes recombine may increase, and conversion efficiency may decrease.If the thickness is too thin, the number of sites where electrons and holes recombine will decrease, but the substrate will reach the collector electrode. In some cases, the lateral flow resistance of the current flowing in the inside increases and the conversion efficiency decreases. For example, boron can be diffused by applying a commercially available coating agent containing boron and drying, followed by heat treatment at 900 to 1050 ° C. for 20 to 60 minutes.

Common silicon solar cell, it is necessary to form only on the light receiving surface of the PN junction, or diffused in a state superimposed two substrates to each other in order to achieve this, SiO ₂ film Ya on the back surface before spreading It is preferable that a SiN _x film or the like is formed as a diffusion mask so that a PN junction cannot be formed on the back surface. In addition to the vapor phase diffusion method, the impurity diffusion layer can be formed by a screen printing method, a spin coating method, or the like.

The antireflection film is preferably a SiN _x film formed using a plasma CVD apparatus or the like, a multilayer film of the SiO ₂ film by the thermal oxide film and the SiN _x film, and the film thickness is preferably 70 to 100 nm.

An electrode is formed on the semiconductor substrate thus obtained by using a screen printing method or the like, but the shape of the electrode is not particularly limited, and the thickness of the bus bar electrode is usually preferably 1 to 3 mm, and 1 to 1 on one side. It is preferable to form four, particularly 2-3. In addition, when a plurality of electrodes are formed on one surface, it is preferable to form these electrodes so as to be parallel to each other.

In the screen printing method, a conductive paste mixed with conductive particles such as aluminum powder and silver powder, glass frit, organic binder, etc. is screen-printed. After printing, the electrode is formed by baking at 700 to 800 ° C. for 5 to 30 minutes. The electrodes are preferably formed by a printing method, but can also be formed by a vapor deposition method, a sputtering method, or the like. In addition, the electrodes on the light receiving surface and the non-light receiving surface can be baked at a time. Thereby, the electrode having the first polarity on the light receiving surface of the first solar cell having the first conductivity type substrate has the second polarity different from the electrode having the first polarity on the non-light receiving surface. Having an electrode. Similarly, an electrode having the second polarity is formed on the light receiving surface of the second solar cell having the second conductivity type substrate, and an electrode having the first polarity is formed on the non-light receiving surface. For example, when an N-type semiconductor substrate is selected as the first conductivity type substrate and a P-type semiconductor substrate is selected as the second conductivity type substrate, the first polarity electrode is a negative electrode, and the second polarity electrode is a positive electrode. It becomes.

The solar cell module of the present invention uses one or more of the first solar cells and the second solar cells described above to connect them alternately, and connects them in series and / or in parallel. The obtained solar battery cell can be sealed with a transparent resin such as EVA (ethylene-vinyl acetate copolymer) to form a solar battery module. Furthermore, it may be a protective structure using a substrate used for a general module together with a sealing resin or a film used for a general module, and any structure such as a super straight structure, a substrate structure, a glass package structure, etc. Also good. Moreover, you may attach the flame | frame which protects a module periphery. Such a solar cell module can be manufactured by a known method such as the method described in JP-A-9-511117.

The preferred embodiment of the solar cell module of the present invention will be described in more detail with reference to the drawings. FIG. 1 shows an example of series connection wiring of solar cells in a general solar cell module, and FIG. 2 shows the solar cell module of the present invention. The example of serial connection wiring of the photovoltaic cell in is shown. In each figure, a is a cross-sectional view and b is a plan view viewed from the light receiving surface side. 1 and 2, 1 is a first solar cell using a first conductive type substrate, 2 is a second solar cell using a second conductive type substrate, 3 is a bus bar electrode, and 4 is a tab. Is a line.

In the general solar battery module of FIG. 1, the module is made using only the solar battery cell using the first conductivity type substrate. Therefore, serial connection is performed by connecting the bus bar electrode on the light receiving surface side and the bus bar electrode on the non-light receiving surface side with a tab line. In order to increase the module conversion efficiency, if the solar cells are arranged as close as possible, the edges of the cells are damaged by the bending stress of the tab wire.

On the other hand, in the solar cell module of the present invention in FIG. 2, the solar cells 1 using the first conductivity type substrate and the solar cells 2 using the second conductivity type substrate are alternately arranged, so that the same surface is obtained. A cell having a first polarity electrode and a cell having a second polarity electrode are present side by side, and series connection is performed by connecting the tab lines between the light receiving surfaces and between the non-light receiving surfaces. ing. As a result, adjacent cells can be arranged close to 3.0 mm or less, particularly 1.0 mm or less. If the distance between the cells is too long, the filling rate of the solar battery cells with respect to the area of the solar battery module may be reduced, and module conversion efficiency may be reduced. Although it is preferable that the distance between the cells is short, if the distance is too short, the cells come into contact with each other and cause cracking, so that the distance is preferably 0.1 mm or more. When installing the outer peripheral frame, the distance between the outer peripheral frame and the solar cell at the module end (outermost row) is preferably 0.1 to 3.0 mm, particularly preferably 0.1 to 1.0 mm. If this interval is too narrow, if the solar cell and the frame overlap with each other, shadow loss may occur and the module conversion efficiency may decrease, and if it is too wide, the filling rate of the solar cell with respect to the area of the solar cell module will decrease, and the module Conversion efficiency may decrease. In addition, what is necessary is just to connect the connection method of a tab wire with solder etc. according to a conventional method.

Next, FIG. 3 shows a wiring example of the entire general solar cell module, and FIG. 4 shows a wiring example of the whole solar cell module of the present invention. Here, an example is shown in which solar cells are arranged in a plurality of rows of 4 × 4 and connected in series. 3 and 4, 1 is a first solar cell using a first conductivity type substrate, 2 is a second solar cell using a second conductivity type substrate, and 5 is a terminal of a first polarity electrode. , 6 indicates the end of the second polarity electrode, and 7 indicates the outer peripheral frame. As can be seen by comparing FIG. 3 and FIG. 4, it can be seen that the solar cell module of the present invention has a higher cell filling rate relative to the module area than a general solar cell module.

Here, the solar cell module of the present invention preferably has a portion in which the first and second solar cells are connected in series, and the first conductivity type substrate is used in this series connection portion. The number of the first solar cells used is preferably 50% to 70%, more preferably 50% to 60%, and the second solar cell using the second conductivity type substrate. The number of battery cells used is preferably 30% to 50%, more preferably 40% to 50%. If either one of the first or second solar cells becomes extremely large, there may be a case where the serial connection wiring that can take advantage of the present invention cannot be made.

Further, the difference in short-circuit current density between the first solar cell and the second solar cell is preferably 20% or less, more preferably 10% or less. If the difference in the short-circuit current density is too large, the short-circuit current density of the solar cell module may be limited to one having a short-circuit current density in the cells connected in series.

EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated more concretely, this invention is not restrict | limited to the following Example. In the following examples, the characteristics of the solar battery cell and the solar battery module are as follows. Using a solar simulator (light intensity: 1 kW / m ² , spectrum: AM1.5 global), short-circuit current density, open-circuit voltage, fill factor, conversion efficiency Was measured.

[Example 1]
As an example, a solar cell module having the structure shown in FIG. 4 was produced as follows.
A solar cell using an N-type silicon single crystal substrate as a first conductivity type substrate and a P-type silicon single crystal substrate as a second conductivity type substrate was prepared. All the prepared cells had a size of 100 mm square.
The average characteristics of the solar cells using the N-type substrate were a short-circuit current density of 35.1 mA / cm ² , an open-circuit voltage of 0.619 V, a fill factor of 78.3%, and a conversion efficiency of 17.0%.
The average characteristics of solar cells using a P-type substrate were a short-circuit current density of 35.1 mA / cm ² , an open-circuit voltage of 0.618 V, a fill factor of 78.5%, and a conversion efficiency of 17.0%.
In the solar cell module, since the solar cells are connected in series, when preparing the cells, the short-circuit current density is equal to the characteristics.

The solar cell module of the present invention was fabricated using 16 pieces of 4 × 4 using the above two types of solar cells. At this time, the gap between the solar cells was 0.5 mm, the gap between the module outer periphery cell and the frame was 1.0 mm, and the frame width was 5.0 mm. The bus bar electrode and the wiring of the next row were connected in the form of protruding the tab wire by 3.0 mm from the cell which is the end of the module in the bus bar direction.
The produced module was 413.5 mm long and 419.5 mm wide including the frame.
The characteristics of the obtained solar cell module were a short-circuit current of 3.50 A, an open-circuit voltage of 9.88 V, a fill factor of 77.9%, and a conversion efficiency of 15.5%.
In addition, although the clearance gap between photovoltaic cells was 0.5 mm, there was no damage to the edge of a cell.

[Comparative Example 1]
As a comparative example, a solar cell module having a general structure shown in FIG. 3 was produced as follows.
As the solar battery cell, only the cell using the first conductivity type substrate of the above example was used, and 16 4 × 4 cells were used. At this time, the gap between the solar cells was 4.0 mm in the bus bar direction, and the gap without tab wiring was 0.5 mm. In addition, the gap between the cells on the outer periphery of the module and the frame, the width of the frame, and the protruding width of the tab line from the cell serving as the end of the module in the bus bar direction were the same as in the above embodiment.
The produced module was 413.5 mm long and 430 mm wide including the frame.
The characteristics of the solar cell module produced in the comparative example were a short-circuit current of 3.51 A, an open-circuit voltage of 9.90 V, a fill factor of 77.4%, and a conversion efficiency of 15.2%.

DESCRIPTION OF SYMBOLS 1 1st photovoltaic cell using 1st conductivity type board | substrate 2 2nd photovoltaic cell using 2nd conductivity type board | substrate 3 Busbar electrode 4 Tab wire 5 Termination of electrode of 1st polarity 6 2nd polarity Electrode end 7 outer frame

Claims (5)

A first conductive type substrate having a light receiving surface and a non-light receiving surface, a first solar cell formed on each of the light receiving surface and the non-light receiving surface and having electrodes having different polarities, a light receiving surface and a non-light receiving surface A second conductive substrate having a surface and second solar cells formed on the light receiving surface and the non-light receiving surface and having electrodes having different polarities are alternately arranged. Solar cell module. The first and second solar cells have a portion connected in series, and in this serial connection portion, the number of used first solar cells is 50% to 70%, and the second solar cell The solar cell module according to claim 1, wherein the number of cells used is 30% to 50%. 3. The solar cell module according to claim 1, wherein the first conductive type substrate is an N type semiconductor substrate, and the second conductive type substrate is a P type semiconductor substrate. The solar cell module according to claim 1, 2, or 3, wherein the distance between the solar cells is 0.1 mm or more and 3.0 mm or less. The solar cell module according to any one of claims 1 to 4, wherein a difference in short circuit current density between the first and second solar cells is 20% or less.

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